Australian general practitioner chlamydia testing rates among young people

Chlamydial infection caused by Chlamydia trachomatis is the most prevalent sexually transmissible bacterial infection in the Western world1 and the most common notifiable infectious disease in Australia.2 In 2009, 62 680 chlamydia diagnoses were reported, with about 80% of these notifications being among young people aged 15–29 years3 — the age group with the highest documented chlamydia prevalence in Australia, with rates of at least 3%–5%.4,5

As chlamydia is mostly asymptomatic,6 regular testing is considered a key public health control strategy;2 if left untreated, infection may have significant clinical consequences such as pelvic inflammatory disease, infertility and pregnancy-related complications.6

Current national guidelines for general practitioners recommend annual screening for chlamydia for all sexually active people aged 15–25 years and those of any age reporting a recent partner change or inconsistent condom use.7 Other clinical guidelines extend testing to the age of 29 years among those who are sexually active.8 A recent mathematical modelling study found that annual chlamydia testing coverage rates of 20% in people aged under 30 years or 40% in those aged under 25 years would halve the prevalence in Australia within 4 years.9

Currently, there is no Australian information on the proportion of 15–29-year-olds tested for chlamydia by GPs. We assessed GP chlamydia testing rates in Australia through analysis of 12 months of Medicare data compiled as part of the Australian Collaboration for Chlamydia Enhanced Sentinel Surveillance (ACCESS; http://www.access-study.org).

We obtained data on all Medicare-rebated GP consultations and chlamydia tests among 16–29-year-olds in Australia from October 2007 to September 2008 (15-year-olds were not included as data were requested from Medicare by 5-year age groups, with 16–19 years being the lowest).

For GP consultations, we obtained data on Group A1 and A2 consultations (specific to GPs), which represented about 80% of all GP consultations. For chlamydia tests, we obtained data on all Medicare chlamydia test claims made by pathology providers outside public hospitals (pathology item numbers 69316, 69317 and 69319).

All calculations were based on each patient’s first test or first consultation during the study period, referred to here as unique tests or unique consultations.

All outcomes were analysed by patient age group, sex and area of residence (metropolitan or non-metropolitan, and state/territory). Metropolitan was defined by the Australian Bureau of Statistics (ABS) Australian Standard Geographical Classification – Remoteness Areas (ASGC-RA)10 as RA 0, and non-metropolitan as RA 1–4 using 2006 concordance data provided by the ABS. Under this classification, the capital cities of the Northern Territory (Darwin) and Tasmania (Hobart) are considered non-metropolitan.

In 2008, the estimated total population of 16–29-year-olds in Australia was 4 195 961. During the study period, 3 139 354 unique GP consultations for 16–29-year-olds were reimbursed by Medicare nationally, meaning that 74.8% of this age group (85.6% of females and 64.4% of males) had at least one GP consultation in the 12-month period. The proportion of the population who had at least one GP consultation was lowest in the NT (54.3%) and highest in Tasmania (79.7%) (Box 1).

To our knowledge, this is the first study to estimate national GP chlamydia testing rates in all 16–29-year-olds who had at least one GP consultation in a year, and also in the sexually active population in this age group. Our analysis found that, despite 86% of females and 64% of males aged 16–29 years visiting a GP in a 12-month period, only 8.9% of those who did were tested for chlamydia. At a population level, we estimate that only 8% of the sexually active people in this age group were tested in general practice for chlamydia.

Previous analyses have estimated GP chlamydia testing rates using population figures rather than patient consultations as the denominator and have only been conducted in Victoria, New South Wales and Tasmania.13-16 Furthermore, the rates found in those studies were considerably lower than those reported here, as the estimates were not adjusted for sexual activity in the populations studied.

Low testing rates may be due to sexual health forming only a small part of a GP’s workload,17 lack of time and knowledge about chlamydia and its risk factors, and patient embarrassment.18 GPs are more likely to test patients who report symptoms or a recent risk event; data from a survey of Victorian GPs19 and from 27 ACCESS general practice sentinel sites have demonstrated this preferential testing. The ACCESS study has found rates of chlamydia positivity about double (9.9% in males and 7.0% in females) that of the chlamydia prevalence estimates reported from community-based studies.4,5

Of all jurisdictions, the NT had the highest testing rate of 16–29-year-olds in the sexually active population and the lowest proportion of this age group who had visited a GP in the 12-month period. The reasons for this are not clear. It is possible that not all GP consultations were reflected in the data or that health care-seeking behaviour was systematically different. Higher testing rates may reflect the targeted screening programs for sexually transmitted infections conducted by government and Aboriginal medical services in the NT20 or a higher-risk population presenting to GPs. It is also unclear why Tasmania had the lowest testing rates, and this warrants further investigation.

On a population level, we believe that Medicare data are useful for estimating testing rates in general practice. However, there are some limitations. First, the testing numerator may have included tests conducted in GP and specialist salaried clinics, such as Aboriginal medical services and family planning clinics, and thus may have overestimated testing rates. A focus on testing conducted at a general practice clinic level would help to overcome this issue. There are two ways this can be achieved: expanding the ACCESS sentinel network, and requesting Medicare practice-level data for future analyses. De-identified practice-level data were unavailable at the time of our study.

Second, “remoteness” may be misclassified if testing is claimed by urban pathology providers for tests conducted on patients residing in non-urban areas. Furthermore, in our analysis, we used the ASGC-RA classification to assess remoteness, which classifies Hobart and Darwin as non-metropolitan, thus precluding meaningful assessment of remoteness as a factor in Tasmania and the NT. Future analyses should consider using the Accessibility/Remoteness Index of Australia classification scheme or McGrail’s index of rural access to ensure Darwin and Hobart are classified as urban.21

Despite these limitations, chlamydia testing rates based on Medicare data provide an important monitoring and evaluation indicator for public health policymakers to assess the impact of local, state and national initiatives such as the Australian Chlamydia Control Effectiveness Pilot.22 Testing rates based on the sexually active population also provide a more appropriate indicator to assess compliance with the clinical guidelines.

Overall, our analyses have demonstrated the need for innovative and evidence-based interventions to increase annual chlamydia testing in primary care. A multifaceted approach may be needed, including medical alerts reminding clinicians of the chlamydia testing guidelines, organisation and optimising of clinic-based registries to remind and encourage patients to seek chlamydia testing annually, education and reimbursement for practice nurses to overcome barriers of GPs’ lack of time and capacity, and the introduction of practice incentive payments to encourage practices to meet nationally defined targets for chlamydia screening.

1 Proportion of the Australian estimated resident population aged 16–29 years with at least one general practitioner consultation, by sex and residence, October 2007 – September 2008

2 General practitioner chlamydia testing rate in 16–29-year-olds per 100 sexually active population, by sex and residence, October 2007 – September 2008